Dr. Jim Metzler just wrote a great article on Service Orchestration. Orchestration refers to the automated arrangement, coordination and management of computer systems, storage, security and networks in order to efficiently deliver application services to end users. The way that orchestration works is that it creates an executable process that involves centrally controlled message exchanges among network entities. As part of the orchestration of network services, the orchestration system provides a layer of abstraction between the application services and the infrastructure. This layer of abstraction is sometimes referred to as Network Services Virtualization (NSV).
The goals of an orchestration system are to maximize the business leverage that can be gained from virtualization and to greatly simplify the management of the pervasive virtualization of data center resources. Therefore, virtualization and orchestration are highly complementary technologies that together enable the implementation of a dynamic data center model. An orchestration system achieves its goals by automating the provisioning and operation of network services.
To learn more, read this article.
